Fujitsu Microelectronics Limited

Norito Hibino

Hiroshi Mawatari

Naoto Emi

Nonvolatile evaluation memory cells are programmed to be a plurality of different values in advance, respectively. An internal voltage generating circuit can change the value of an internal voltage according to adjusting signals. To make the internal voltage close to its expected value, a voltage adjusting circuit outputs adjusting signals in accordance with cell currents that flow through the evaluation memory cells, respectively, in a read operation on the evaluation memory cells. As a result, the interval voltage that is shifted from its expected value due to variations in manufacturing conditions can automatically be set to the expected value by using the adjusting signals. Since an internal circuit operates on a correct internal voltage, operation margins can be increased. The yield of a nonvolatile semiconductor memory can thus be increased.

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Kawasaki, Japan

Norito Hibino